Threat Bulletin 1378: HTTP POST flood against a retail banking platform in the Nordics

On Friday 5 June 2026 at 17:50 UTC, a HTTP POST flood targeted a retail banking customer in the Nordics. The attack peaked at 260.2 million requests per second and lasted 104 minutes. Traffic originated from 3841 autonomous systems in 98 countries, predominantly a rented booter service.

Vector HTTP POST flood
Peak 260.2 million requests per second
Duration 104 min
Time to mitigation 0.586 s
Attack traffic reaching origin 0.045%
Legitimate traffic challenged 0.43%

Timeline

The attack was preceded by a publicly announced sales event. Request rates on the targeted routes exceeded their hourly baseline by a factor of 731 within 32 seconds. The risk score of participating clients crossed the challenge threshold automatically and proof-of-work difficulty rose with origin load.

What the customer saw

No customer-visible impact. The on-call engineer was notified and acknowledged the incident from the dashboard.

Recommendations

  • Review allow-listed partner ranges quarterly.
  • Lower challenge thresholds on authentication endpoints during high-risk events.
  • Enable log streaming to your SIEM for faster correlation.

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